JP4159634B2 - Metallic iron manufacturing method and equipment - Google Patents

Abstract

A method of making metallic iron includes heating a mixed powder containing iron oxide and a carbonaceous reducing agent on a hearth to reduce the iron oxide and melt the reduced iron. Preliminary molding of the mixed powder starting material into pellets is not required. The resulting metallic iron contains extremely low concentrations of slag ingredients, even when the mixed powder starting material contains only low concentrations of iron oxide.

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an improvement in a technique for obtaining metallic iron by heating and reducing iron oxide such as iron ore together with a carbonaceous reducing agent such as a carbonaceous material. The iron oxide is reduced to metallic iron by a simple treatment, and iron oxide The present invention relates to a method and an apparatus capable of separating a slag component mixed as a gangue component in a source and efficiently producing it as high-purity metallic iron.
[0002]
[Prior art]
As a direct iron manufacturing method for obtaining reduced iron by directly reducing iron oxide such as iron ore and iron oxide pellets with a carbonaceous material or a reducing gas, a shaft furnace method represented by the Midrex method has been known. This type of direct iron manufacturing method is a method in which reducing gas produced from natural gas or the like is blown from the tuyere at the lower part of the shaft furnace and iron oxide is reduced using the reducing power to obtain metallic iron. Recently, a reduced iron production process using a carbonaceous material such as coal as a reducing agent in place of natural gas has attracted attention. Specifically, the so-called SL / RN method has already been put into practical use.
[0003]
As another method for producing reduced iron, U.S. Pat. No. 3,443,931 discloses that a carbonaceous material and powdered iron oxide are mixed to form a lump or pellet, and heat reduced on a rotary hearth to obtain reduced iron. A manufacturing process is disclosed.
[0004]
The reduced iron produced by these methods is used as an iron source after being formed into a briquette or the like as it is and then charged into an electric furnace or the like. In recent years, as iron scrap recycling has become active, reduced iron obtained by the above method has attracted attention as a diluent for impurity elements mixed in scrap.
[0005]
However, the reduced iron obtained by the conventional reduced iron making method includes SiO contained in iron oxide (eg gangue in iron ore) and carbonaceous material (eg ash in coal) used as a raw material. ₂ , Al ₂ O _Three Since slag components such as CaO are mixed in a large amount, the iron quality (purity as metallic iron) of the product is lowered.
[0006]
In practical use, these slag components are separated and removed in the next refining process, but an increase in the amount of slag not only reduces the yield of the refining melt, but also adversely affects the operating cost of the electric furnace. Reduced iron with high grade and low slag component content is required, but to meet these requirements with the conventional reduced iron manufacturing method as described above, iron ore with high iron grade must be used as a raw material for producing reduced iron. Therefore, the selection range of practical steelmaking raw materials will be greatly narrowed.
[0007]
Furthermore, in the conventional method as described above, an iron oxide source and a carbonaceous material must be mixed and preliminarily formed into a lump shape, a pellet shape, or the like, and an increase in the burden required for pre-forming facilities and operations is inevitable.
[0008]
Furthermore, as another direct reduction iron manufacturing method, Japanese Patent Application Laid-Open No. 8-27507 discloses that a carbonaceous reducing agent powder containing a desulfurizing agent and an iron oxide powder are layered on a movable hearth, respectively, and heated to form a sponge. A method for obtaining iron is disclosed. According to this method, the iron oxide is reduced by the carbonaceous reducing agent, and the sulfur component contained in the carbonaceous reducing agent such as coal is captured by the desulfurizing agent. It is emphasized that it can be obtained and the subsequent desulfurization load is reduced.
[0009]
However, this method has the advantage that the iron oxide raw material does not need to be preformed into pellets or the like, but the reduction efficiency is low because the iron oxide source and the carbonaceous reducing agent are not in direct contact, and a long time is required for the heating reduction. However, it is not suitable for practical use on an industrial scale in terms of productivity. Moreover, the conventional method described above is a method of obtaining reduced iron in the form of sponge iron, so that the gangue component in the sponge iron is not separated, and the iron quality as reduced iron is lowered. If such reduced iron grade reduced iron is supplied as an iron source to an electric furnace or the like, not only will the slag increase the amount of produced slag, but the operability of the electric furnace will be adversely affected. Many problems occur, such as an increase in units and a decrease in productivity. Moreover, since the above problem appears more prominently when the iron content of the iron oxide source used is low, it is almost impossible to use a low-grade iron oxide source as a raw material for actual operation. Only high-quality iron oxide sources can be used.
[0010]
[Problems to be solved by the invention]
The present invention has been made in view of the problems of the prior art as described above, and the purpose thereof is not to require preliminary preforming into a lump or pellet, and a high-grade iron oxide source is Of course, even from a low-grade iron oxide source, a technique for efficiently producing reduced iron with a small amount of mixed slag components and high Fe purity is to be established.
[0011]
[Means for Solving the Problems]
In the production method according to the present invention, which was able to solve the above-mentioned problems, a mixture of iron oxide-containing powder and carbonaceous reducing agent-containing powder was laid on the hearth as a mixed powder without being previously formed into pellets or the like. There is a gist where it is heated, reduced and melted. In carrying out this method, if the mixture laid on the hearth is pressed and consolidated and then heated, the contact between the iron oxide source and the carbonaceous reducing agent becomes more dense, and the heating reduction efficiency It is preferable to increase the heat-reducing efficiency by increasing the effective heating area.
[0012]
Further, in the present invention, the mixture laid on the hearth is heated and reduced / melted as described above, and the molten high specific gravity reduced iron is brought into direct contact with the hearth surface and the fire resistance of the floor surface is increased. When the product is thermally deteriorated, or when the product is discharged from the floor after reductive melting, the reduced iron may adhere to the floor and impair the discharge. It is preferable to form a bed leaving acceleration layer that also serves as a bed because the discharge of the product from the hearth can be facilitated and the life of the hearth can be extended. Also, when carrying out this method, if a desulfurizing agent is included in the mixture, the sulfur content generated in the heating reduction / melting step is captured by the desulfurizing agent, and the sulfur content of the resulting reduced iron is reduced. Since it can reduce, it is preferable.
[0013]
Furthermore, the apparatus for producing metallic iron according to the present invention is an apparatus preferably used for carrying out the above-mentioned production method, and is a movable hearth, and a mixture of iron oxide-containing powder and carbonaceous reducing agent-containing powder on the hearth. Supply mechanism, a heating mechanism for heating the mixture on the hearth, a discharge mechanism for discharging the product reduced and melted by heating to the outside of the hearth, and a separation for separating the product into reduced iron and slag components It is characterized by having a mechanism.
[0014]
Also in this apparatus, a pressing mechanism for pressing the mixture laid on the hearth is provided, or an unevenness forming mechanism for forming unevenness on the layer of the mixture is provided, or further, thermal protection is provided on the hearth. It is recommended as a preferred embodiment to provide a bed-promoting layer forming mechanism for forming a bed-promoting layer that also functions as a bed.
[0015]
Further, the hearth in the apparatus comprises a plurality of hearth units that move along a closed loop, or a plurality of hearth units that reciprocate, and a rotating disk-shaped hearth, or The inside of the horizontal cylindrical refractory furnace is composed of a plurality of hearth units that rotate coaxially so that a series of processes from supplying the raw material mixture to heating reduction / melting and discharging the product can be continued. It is recommended as a preferred form when implementing this apparatus on an industrial scale.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
As described above, in the production method of the present invention, a mixture of iron oxide-containing powder and carbonaceous reducing agent-containing powder (hereinafter sometimes referred to as carbonaceous material) is heated on a hearth and reduced / melted. In this method, since the iron oxide source and the carbonaceous material are mixed and used in a powder state, preforming into a lump or pellet is unnecessary, and this method is also possible. For example, the iron oxide source and the carbonaceous material are mixed in powder form and subjected to heat reduction in a state where they are adjacent to each other, so that the heat reduction proceeds quickly, and the reduction can proceed efficiently with a relatively short heat treatment. it can. Further, in this method, the reduced iron produced by the heat reduction is subsequently heated and melted, and the metal irons are fused and assembled together while eliminating the slag component, so an iron oxide source having a low iron quality is used. Even in this case, it is possible to obtain reduced iron having a very small Fe content and a very small amount of slag components.
[0017]
Hereinafter, the production method and apparatus of the present invention will be described in more detail with reference to the drawings showing an example of the apparatus for producing metallic iron according to the present invention. However, the present invention is not limited to the illustrated examples. However, it is also possible to change the design appropriately within a range that can meet the purpose described above and below, and these are naturally included in the technical scope of the present invention.
[0018]
1 and 2 illustrate a metallic iron manufacturing apparatus according to the present invention. FIG. 1 is a schematic plan view illustrating the ceiling portion opened, and FIG. 2 is a schematic cross-sectional explanatory view of FIG. In the figure, 1 is a heating furnace, 2a and 2b are raw material supply sections, 3a and 3b are hearth units, 4 is a rail for moving the hearth unit, 5 is a burner constituting a heating mechanism, and 6 is a separation mechanism. Each of the constituting melting separation furnaces is shown.
[0019]
In this example, pallet-shaped hearth units 3a and 3b are arranged so as to be able to reciprocate by a rail 4 in a heating furnace 1 provided in the center with the raw material supply parts 2a and 2b interposed therebetween as shown in the figure. In the raw material supply unit 2a (or 2b), supply a mixture of an iron oxide source and a carbonaceous material in the hearth unit 3a (or 3b) and lay it at an appropriate thickness. In some cases, the mixture layer is pressed and consolidated, Furthermore, after forming unevenness on the surface, it is moved into the heating furnace 1 (in FIG. 1, after the raw material mixture is supplied into the hearth unit 3a by the raw material supply part 2a in the upper part of the drawing, the unit 3a is heated in the heating furnace. In this portion, reduction and melting are advanced by heating with the burner 5.
[0020]
The iron oxide source in the raw material mixture laid on the hearth unit 3a and sent into the heating furnace 1 receives heat from the burner 5 and is produced by the carbon material in the mixture and the carbon monoxide generated from the carbon material. It is reduced and further heated and melted while receiving the carburization of carbon from the adjacent carbonaceous material. During this time, the molten reduced iron adheres to each other while collecting by-product slag components and gathers, and gradually grows into a large molten iron mass. Therefore, when heated in the heating furnace 1 for a predetermined time, in the hearth unit 3a, the reduced iron in a molten state produced by reduction and adhered to each other becomes a large lump. As described above, the reduced iron in a molten state adheres to each other while excluding the slag component, and the slag component is not substantially mixed in the inside only by the slag component adhering to the surface.
[0021]
After the reduction / melting is completed, the hearth unit 3a is tilted in the direction of the melting separation furnace 6 by an arbitrary tilting means (not shown), and the product is discharged from the hearth unit 3a in the direction of the melting separation furnace 6. When the temperature is lowered, the molten separation furnace 6 is further heated to maintain fluidity, and the reduced iron Fe and slag S are separated by the difference in specific gravity, and the slag S is separated from the surface layer side and the metallic iron from the lower part. Fe is extracted.
[0022]
The hearth unit 3a that has finished discharging the product is moved to the raw material supply unit 2b provided on the lower side of FIG. 1, and the hearth unit 3b that has been waiting for the raw material supply unit 2a after supplying the raw material is heated. The raw material mixture is heated and reduced and melted in the same manner as described above. During this time, the raw material supply unit 2b below the drawing supplies the raw material to another hearth unit (or presses it, forms surface irregularities), and waits for the next heating reduction / melting. And when discharge | emission of the reduction product from the hearth unit which finished heating reduction and melting in the heating furnace 1 is complete | finished, while moving this hearth unit upwards in drawing, it is taken out from the heating furnace 1, and raw material supply part 2b The hearth unit that has been waiting in step 1 is fed into the heating furnace 1. By repeating this operation, the raw material mixture can be heated and reduced and melted intermittently and continuously.
[0023]
When such a method is carried out, the exhaust gas discharged from the heating furnace 1 contains a considerable amount of heat and combustible gas. Therefore, if this exhaust gas is recycled as fuel for the burner 5, it contributes to fuel cost savings. It can also be used effectively as a heating source or fuel for nearby facilities.
[0024]
Further, in preparing the raw material mixture for carrying out this method, a carbon material of a theoretical amount or more necessary for the reduction of iron oxide contained in the iron oxide source is blended, but more preferably, “raw iron oxide” It is desirable to adjust the blending amount of the carbon material so as to satisfy “amount required for reduction of iron + amount required for carburization of reduced iron + amount of oxidation loss”. Therefore, when the reduced iron produced in the heat reduction step is carburized in a heat reduction atmosphere, the melting point is lowered and separation from the slag component becomes easier. Therefore, it is desirable to adjust the blending amount of the carbon material in consideration of the theoretical amount necessary for the reduction of the raw iron oxide, the above carburizing amount, and further the oxidation loss amount in the heating furnace.
[0025]
The raw material mixture laid on the hearth unit is laid so as to have an appropriate thickness as a powdery mixture. The thickness at this time may be appropriately determined in consideration of the configuration, scale, heating efficiency, etc. of each manufacturing apparatus, but is preferable for efficiently heating the mixture layer to the inside to promote reduction / melting efficiently. The thickness is in the range of 10 to 300 mm, more generally 20 to 100 mm.
[0026]
Note that the raw material mixture may be laid on the entire surface of the hearth unit with almost the same thickness, or as described above, it can be appropriately suppressed with an arbitrary pressing device to be compacted or uneven on the surface to increase the effective heating area. It is also possible to place a plurality of pieces in an arbitrary shape such as a trapezoidal shape with an appropriate gap on the hearth unit, and in the present invention, “laying on the hearth” means such a placing method. Is also included.
[0027]
The raw material mixture laid on the hearth unit may be only made uniform by an appropriate leveling mechanism, but when pressed by a pressing roller or the like, the raw material mixture is made compact, and the iron oxide and the carbonaceous material are brought into closer contact with each other. This is preferable because the reduction efficiency can be further increased.
[0028]
Further, when such pressing treatment is performed, if the surface area is increased by forming irregularities on the surface of the pressing layer, heat from above can be efficiently transferred to the inside of the mixture layer, and CO generated by a reduction reaction. ₂ The release of gas is also accelerated, which is preferable because the reduction efficiency can be further increased. The shape of the unevenness is not particularly limited, and can be any shape such as a linear shape, a wavy shape, a lattice shape, etc., but the unevenness is formed so as to partition the pressing layer into an appropriately sized lattice shape. In this case, the metallic iron produced by heat reduction in each lattice gathers as one molten lump and forms as a lump of metal iron of almost uniform size, so that the subsequent treatment (by sieving with the slag component) This is preferable because it facilitates standardization of separation operations and the like.
[0029]
The operating temperature at the time of heating reduction is not particularly limited as long as it is higher than the temperature at which the metallic iron produced by the reduction or its carburized material can be melted. In order to advance the heat reduction efficiently while suppressing the temperature to 1350 to 1550 ° C, more preferably in the range of 1400 to 1500 ° C.
[0030]
3 to 6 show other embodiments of the present invention, FIG. 3 is a schematic plan view, FIG. 4 is a schematic longitudinal sectional view of the region A in FIG. 3, and FIGS. The schematic sectional explanatory drawing of the BB line and CC line part is shown, respectively.
[0031]
In the apparatus of this example, a large number of hearth units 3, 3,... Are arranged on a moving mechanism that continuously swivels along a track-shaped closed loop, and swivels along the track-shaped loop. In this process, it is possible to continuously perform the operations of supplying the raw material mixture → pressing / consolidating (and forming unevenness) → heating reduction / melting → discharging the product.
[0032]
That is, in FIG. 3, 7a and 7b are raw material supply sections, 8a and 8b are pressing (or further uneven formation) sections, D and E areas are heating reduction zones, and 9a and 9b are product discharge sections. The track-like loop is divided into two parts, and a structure in which two steps of heat reduction and melting can be continuously performed in one loop is shown.
[0033]
The raw material supplied to the hearth unit 3 by the raw material supply units 7a and 7b is pressed by the pressing units 8a and 8b to be consolidated, and then sent to the heating zones D and E. In this region D and E, the burner The heat reduction proceeds by receiving heat from a heating mechanism such as 5. Then, the hearth pallet 3 which has been reduced and melted and has reached the discharge portions 9a and 9b is tilted by an arbitrary tilting means as shown in FIGS. The reduced iron Fe and the generated slag S are separated sequentially by the specific gravity difference.
[0034]
Further, in this example, as shown in FIGS. 3 and 4, raw material secondary supply parts 10a and 10b are provided at substantially intermediate portions of the heating zones D and E so that the raw material mixture can be secondarily supplied. In other words, even if the raw material supplied as a powdery mixture is pressed, the volume is reduced to about 1/2 to 1/3 times due to the combustion of carbonaceous material and the reduction of iron oxide in the heating reduction / melting process. Therefore, if the continuous operation is continued as it is, the effective treatment capacity (internal capacity) of the hearth unit 3 cannot be fully utilized in the latter half of the heating reduction. Accordingly, when the volume of the raw material mixture in each hearth unit 3 is reduced during the heating reduction as shown in the drawing, an amount of the raw material mixture corresponding to the reduced capacity is additionally charged from the secondary supply units 10a and 10b. Continued heating and reduction is extremely effective for increasing productivity.
[0035]
FIG. 7 is a schematic longitudinal sectional view showing another embodiment of the present invention, in which a plurality of hearth units 3, 3... Are fixed to a caterpillar type swivel drive device, and a raw material mixture is supplied → pressed and consolidated. It is configured such that a series of steps of conversion → heating reduction / melting → discharge can be continuously performed along a closed loop. That is, as shown in the figure, the raw material powder is supplied onto the hearth unit 3 from the raw material supply unit 7 at the upper right end of the closed loop, and the raw material powder is pressed by the pressing roller 8, and irregularities are formed if necessary, followed by the burner. Reduction and melting are carried out in the same manner as described in the illustrated example by sending to the heating unit 1 having a heating mechanism such as 5 and heating it. Then, the product is cooled by the cooling mechanism 12 provided on the downstream side of the heating unit, and when reaching the right end of FIG. 7, the hearth unit 3 tilts in accordance with the turning, and the product is separated from the hearth unit 3. Then it falls down naturally with its own weight. Therefore, it is only necessary to receive the product below and separate the metal iron and slag by magnetic separation after pulverization.
[0036]
In carrying out this method, it is necessary to make it possible for the product to easily peel off from the hearth unit 3 and fall, and as a means for this purpose, in this example, the bed is left below the closed loop. A promoter supply unit 13 is provided, and a bed promoter such as a MgO suspension is attached to the receiving surface of the hearth unit 3 at this portion. The bed leaving accelerator facilitates the separation of the product from the hearth unit surface as described above, and is preferably mixed in a compound having a melting point higher than that of reduced iron or generated slag, or in the generated slag. Any compound can be used as long as it is a compound that increases the melting point of slag, but MgO, CaO, Al are particularly preferable in view of the effect of promoting bed leaving, cost, and the like. ₂ O _Three Or a complex oxide containing these. If these bed leaving accelerators are allowed to adhere to the hearth unit surface, not only the product can be released easily as described above, but also the thermal deterioration of the surface of the hearth unit can be suppressed, and the extension of the service life can be enhanced. It is also preferable because it can be performed. In addition to the illustrated example, the bed leaving accelerator may be supplied in the form of powder before the raw material mixture supply unit, for example.
[0037]
Also in the example of FIG. 7, exhaust gas discharged from the heat reduction / melting part is recovered through the duct 14 so that the retained heat and contained combustible gas can be effectively used as thermal energy and fuel.
[0038]
FIGS. 8 and 9 are a longitudinal sectional explanatory view and a transverse sectional explanatory view showing still another embodiment of the present invention, in which heating reduction / reduction is performed on a disk-shaped hearth 3 rotating in a furnace formed in a donut shape. An apparatus for melting is shown.
[0039]
That is, this apparatus is configured such that a disk-shaped hearth 3 rotates like a turntable in a doughnut-shaped heating furnace 1, a raw material mixture is supplied from a raw material supply unit 7, and the pressure roller 8 supplies the mixture. After pressing, reduction / melting is advanced by heat from the burner 5. Next, after the reduction product is cooled in the cooling zone 12, the product is discharged from the floor surface by a screw-type discharge mechanism 15 provided downstream thereof, and the slag component and the reduced iron are removed by a sieve or a magnetic separator not shown. Separation. Even when this method is carried out, a bed leaving accelerator is applied or sprayed immediately upstream of the raw material supply unit 7 to promote bed leaving and to suppress thermal deterioration of the hearth. It is also effective to increase the heat reduction efficiency by forming irregularities on the surface, and to make effective use of the exhaust gas from the heating section.
[0040]
FIG. 10 is a schematic sectional view showing still another embodiment according to the present invention, and has a plurality of hearth units 3a, 3b, 3c,... Rotating coaxially in a horizontal cylindrical refractory furnace A. And having a structure in which these are rotated along the inner peripheral wall of the refractory furnace A by an arbitrary drive source, a raw material supply section 7 and a product discharge section 9 are provided at arbitrary positions of the refractory furnace A, and A preheating burner 5a is provided at a position immediately before the raw material supply position along the rotation direction of the hearth unit, and heating burners 5b, 5b,... ing.
[0041]
When reduction / melting is performed using this apparatus, the raw material mixture is loaded into the furnace A from the raw material supply unit 7 until the hearth unit 3a preheated by the preheating burner 5a rotates and reaches the raw material supply unit 7. Enter. The charged raw material mixture is sequentially reduced by receiving heat from the burner 5b while rotating on the hearth unit 3a, and reduced iron is generated and slag components are sequentially separated. On the downstream side, cool air is sent from the air cooling unit 12 to cool and solidify the metallic iron and slag components generated by reduction and melting, and are sequentially discharged from the product discharge unit 9 to the outside of the furnace A. Separates iron and slag components. By performing this operation continuously, that is, charging of the raw material mixture → heating reduction / melting → cooling solidification → discharge → separation of metallic iron, reduced iron can be continuously produced.
[0042]
In the above, the example in which the metallic iron produced by reduction / melting is once cooled and solidified in the furnace A and then discharged out of the furnace A is shown. It is also effective to melt the reduced iron and the slag component in a molten state after melting all of the reduced iron and slag components.
[0043]
The method and apparatus of the present invention are configured as described above, for example, and the greatest feature thereof is that, as described above, the iron oxide source and the carbonaceous reducing agent powder are heated and reduced in a mixed state, and the produced reduced iron is obtained. By separating the slag component from the molten state in a molten state, the mixing of the slag component into the metallic iron is suppressed, and it is characterized by obtaining reduced iron with high Fe purity. Even from a low-grade iron oxide source having a low iron oxide content as well as a reduced iron oxide source, it is possible to obtain reduced iron with an extremely high Fe purity, for example, with an Fe content of 95% or more, more preferably 98% or more. . Therefore, the present invention can effectively recover the Fe content even from a waste containing a small amount of iron oxide, for example, discharged as blast furnace dust, and the slag separated by adopting the method and apparatus of the present invention. It is also effective to increase the recovery rate of Fe by recycling iron as a raw material and further recovering the iron oxide content mixed in a small amount in the slag.
[0044]
By the way, as the carbonaceous reducing agent used by mixing with the iron oxide source, coal powder and coke powder are the most common, but since these contain a considerable amount of sulfur, the heating reduction step A considerable amount of sulfur is mixed in the reduced iron produced in step 1, which may increase the desulfurization load in the subsequent refining process. However, when practicing the present invention, an appropriate amount of a desulfurizing agent containing, for example, calcium carbonate, sodium carbonate, calcium chloride, or the like is contained in the raw material mixture, and the sulfur content generated in the heat reduction step is used as the desulfurizing agent. If it can be captured and separated and removed together with the slag, the sulfur content of the obtained reduced iron can be reduced as much as possible.
[0045]
【Example】
Hereinafter, the present invention will be described in detail with reference to examples. However, the present invention is not limited by the following examples, and is suitably within a range that can meet the purpose described above and below. It is also possible to change and implement, and all are included in the technical scope of the present invention.
[0046]
Example 1
The iron ore powder and coal powder having the following composition are uniformly mixed in the following ratio, and the mixture (average particle size: 35 μm) is laid on a refractory material tray so that the thickness becomes 100 mm □ × thickness 40 mm. The sample was charged into an electric furnace and heated at 1400 ° C. in a nitrogen gas atmosphere, and the change of the mixture was observed from a viewing window.
[0047]
As a result, the reduction of the iron ore progresses over time, and the molten reduced iron is generated in the form of dots, and then successively adheres and collects. After about 50 minutes, the molten reduced iron lump and slag are mixed. separated. Thereafter, it is cooled and the tray is taken out from the electric furnace, and a plurality of metallic iron ingots having a metallic luster and black slag having the following composition are obtained.
[0048]
Raw material mixture
Iron ore powder composition (wt%)
T. T. Fe: 69.4%, FeO: 30.1%, SiO ₂ : 1.75%
Al ₂ O _Three : 0.49%, CaO: 0.45%
Coal powder composition (% by weight)
Fixed carbon: 68.5%, volatile content: 21.4%, ash content: 10.1%
Iron ore powder: Coal powder = 76.9%: 23.1%
Product composition (wt%)
Reduced iron ingot
T. T. Fe: 96.75%, FeO: 0.31%, M.P. Fe: 96.39
, Total carbon: 2.22%, Metallization rate: 99.63%
Slug
T. T. Fe: 5.15%, FeO: 0.56%, M.P. Fe: 4.58%,
SiO ₂ : 44.63%, Al ₂ O _Three : 19.18%, CaO:
10.36%
[0049]
Example 2
A mixture (average particle size: 35 μm) in which the same iron ore powder and coal powder as used in Example 1 were uniformly mixed at the same ratio was trapezoidal (upper surface 20 mm □ × lower surface 35 mm □) in a refractory material tray. Nine of them were raised side by side in a state of being consolidated to a thickness of 30 mm), charged in an electric furnace, heated at 1400 ° C. in a nitrogen gas atmosphere, and the change of the mixture was observed from the viewing window.
[0050]
As a result, the reduction of the iron ore progresses over time, and the reduced iron in the molten state is generated in the form of dots, and then the reduced iron is sequentially attached and assembled every nine blocks. After about 17 minutes, Nine molten iron ingots were formed in the tray. Then, after cooling and taking out the tray from the electric furnace, nine metallic iron ingots and black slag having a metallic luster having the following composition are obtained.
[0051]
Product composition (wt%)
Reduced iron ingot
T. T. Fe: 96.35%, FeO: 0.30%, M.P. Fe: 95.96
%, Total carbon: 2.75%, metallization rate: 99.59%
Slug
T. T. Fe: 10.66%, FeO: 2.37%, M.M. Fe: 8.57
%, SiO ₂ : 49.42%, Al ₂ O _Three : 17.40%,
CaO: 9.51%
[0052]
【The invention's effect】
As described above, according to the present invention, reduced iron with high Fe purity can be obtained very simply and efficiently by heating and reducing and melting the mixed powder of the iron oxide source and the carbonaceous reducing agent as they are or in a compacted state. Can do. In particular, in the present invention, there is no need for preforming into a lump or pellet form as in the direct reduction iron making method currently most commonly performed, and the iron source and the reducing agent are in contact with each other quickly. Since the reduction reaction proceeds, the reduction efficiency is very high. In addition, the reduced iron produced by reduction collects and adheres to each other while excluding slag components in the molten state, so when using a high-quality iron oxide source, iron oxide with low iron quality is used. Even when a source is used, reduced iron having a very high Fe purity with a small amount of mixed slag components can be easily obtained. Therefore, iron is effectively used not only from low-grade iron ore raw materials that were previously impractical as industrial-scale direct iron-making raw materials, but also from waste materials with low iron content discharged as blast furnace dust, etc. It becomes possible to collect. Moreover, if the apparatus of this invention is used, the direct reduction iron manufacture using a powdery raw material mixture can be continued, and it can respond easily also to mass production on an industrial scale.
[Brief description of the drawings]
FIG. 1 is an explanatory plan view of an essential part showing an embodiment of the present invention.
FIG. 2 is a cross-sectional equivalent view of the apparatus shown in FIG.
FIG. 3 is a schematic plan view showing still another embodiment according to the present invention.
4 is a schematic longitudinal cross-sectional explanatory view showing an enlarged view of a heating reduction / melting part and a separation part of the apparatus shown in FIG. 3;
5 is a cross-sectional explanatory view taken along line BB in FIG. 3. FIG.
6 is a cross-sectional explanatory view taken along the line CC in FIG. 3;
FIG. 7 is a schematic longitudinal sectional view illustrating still another embodiment according to the present invention.
FIG. 8 is a schematic longitudinal sectional view showing still another embodiment according to the present invention.
9 is an explanatory diagram of a transverse section in FIG. 8. FIG.
FIG. 10 is a schematic cross-sectional explanatory view showing still another embodiment according to the present invention.
[Explanation of symbols]
1 Heating furnace (heating unit)
2,2a, 2b Raw material supply section
3, 3a, 3b hearth or hearth unit
4 rails
5 Burner (heating mechanism)
6 Separation section (melting separation furnace)
7, 7a, 7b Raw material supply section
8, 8a, 8b Pressing roller (pressing mechanism)
9, 9a, 9b Product discharge section
10, 10a, 10b Raw material secondary supply section
12 Cooling zone
Fe reduced iron
S slug
A Horizontal cylindrical refractory furnace
5a Preheating burner
5b Heating burner

Claims (11)

The mixed powder of an iron oxide containing powder and a carbonaceous reducing agent containing powder,-out mat on a movable hearth and heating and pressing the mixed powder, thereby melting all reduced iron and slag by the reduction and melting A manufacturing method of metallic iron. A process according to claim 1 is heated by forming irregularities on the layer of the mixed powder. Compound of melting point higher than a pre-reduced iron and generated slag in said furnace floor, or according to claim 1 or 2 mixed into produced slag carried out to form a lifting promoting layer made of a compound to increase the melting point of the slag Manufacturing method. The process according to any one of claims 1 to 3 , wherein the mixed powder further contains a desulfurizing agent. A movable hearth, a supply mechanism for supplying a mixed powder of iron oxide-containing powder and carbonaceous reducing agent-containing powder onto the hearth, a pressing mechanism for pressing the mixed powder laid on the hearth, and the furnace a heating mechanism for heating the mixed powder on the floor, and a discharge mechanism for discharging the products present reduction and melting is melted all reduced iron and slag by heating to hearth out, separating the product into reduced iron and slag An apparatus for producing metallic iron, comprising: a separation mechanism that performs the separation. The apparatus of Claim 5 provided with the uneven | corrugated formation mechanism which forms an unevenness | corrugation in the layer of the said mixed powder . A mechanism for forming a bed separation promoting layer is provided on the hearth to form a bed separation promoting layer composed of a compound having a melting point higher than that of reduced iron or produced slag, or a compound mixed in the produced slag to increase the melting point of the slag . Item 7. The device according to Item 5 or 6 . The hearth is, apparatus according to any of constituted claims 5-7 in a plurality of hearth units moving along a closed loop. The hearth is, apparatus according to any of constituted claims 5-7 in a plurality of hearth units reciprocates. The apparatus according to any one of claims 5 to 7 , wherein the hearth has a rotating disk shape. The hearth is, inside the lateral cylindrical refractory furnace A device according to any one of constituted claims 5-7 in a plurality of hearth units arranged in the circumferential direction of the cylinder.

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